An embodiment of a microfluidics system as referred to above is known from US 2005/0019898 A1. This document describes a fluid mixing device comprising a chamber comprising two diaphragm regions. The diaphragm regions are displaced into and out of the chamber by inflation and deflation of two mixing bladders to generate fluid movement within the chamber. Mixing results from the fluid movement obtained by operating the mixing bladders and diaphragm regions. It is a drawback of the known device that the mixing can be improved and that the mixing bladders and associated means for inflating and deflating the mixing bladders take-up volume. The fluid cannot be removed from the mixing chamber except by replacing with another fluid (air) which requires another fluid source and additional sealing measures.